1. Field of the Invention
The present invention relates generally to a sprinkler head on which a lodgement preventive measure is effected among the sprinkler heads for extinguishing a fire, and more particularly, to a sprinkler head which includes a packing engaged with a frame, for preventing the lodgement.
2. Description of the Prior Art
In the sprinkler head having a horse-shoe-shaped arm, as illustrated in FIG. 7, a valve body 30 is knocked straight down by an extinguishing liquid spurting out during an operation. In some cases, the valve body 30 or other parts may lodge on a boss 14. This phenomenon is known as a lodgement. If the lodgement takes place in the sprinkler head when the fire occurs, the extinguishing liquid, which is originally sprinkled uniformly by a deflector, is sprinkled in irregular directions through the valve body. Thus, normal fire-extinguishing activity can not be performed. It is an ironclad rule that lodgement should be avoided in the sprinkler head.
A multiplicity of sprinkler heads on which the lodgement preventive measures are effected have hitherto been proposed. (See: Japanese Utility Model Publication Nos. 10698/1982, 52456/1982 and Japanese Utility Model Laid-Open Nos. 26660/1984, 102053/1984, 159455/1984, 151750/1986.
Those sprinkler heads for preventing the lodgement all exhibit the lodgement preventive effects. In the sprinkler head in which the valve body is machined, however, it is difficult to machine a hard valve body. This presents problems in terms of machining accuracy and prices. On the other hand, the sprinkler heads in which the packing is machined have such characteristics that there is no problem in accuracy because of such thin, soft packing as compared with the sprinkler head including the machined valve, and the packing is easy to machine. Namely, among the lodgement preventive sprinkler heads, the sprinkler head disclosed in Japanese Utility Model Publication No. 42456/1982 is the most excellent one in terms of manufacturing and price, wherein the packing engages with a frame (hereinafter referred as a packing engagement type).
It is a rare case that the lodgement is caused even in the sprinkler head on which no lodgement preventive measure is effected generally when being attached to a pipe. Besides, there is almost no possibility of causing the lodgement in the packing engagement type. When performing an experiment for the occurrence of lodgement under conditions favable to such a lodgement, the lodgement, though very slight, may take place even in the packing engagement type sprinkler head. The sprinkler head is not allowed to cause the lodgement even during the experiment, because this implies its possibility in the practical use.